We live in the age of unity. "Synthesis," "integration," "cohesion" and similar catchwords have come to dominate virtually every area of human endeavor, from business to art, from scientific theory to personal relationships.

No doubt, all this harmony is a good thing. But at times, something within us resists the call to break down yet another boundary, to erase yet another distinction. Something within us protests that certain things just don't mix, that the combination of two very different realities will often result in a hybrid that is neither here nor there, rendered useless or worse by its inherent contradictions.

This is the essence of the Torah's kilayim laws, which are a series of prohibitions against the intermixing of certain breeds and species. While the Torah is obviously in favor of unity and harmony—indeed, its stated function is "to bring peace into the world" and reveal the underlying oneness of a reality created by the One G‑d—the Torah is also the guardian of the boundaries which G‑d established in His creation. The Torah's concept of "peace" is not the indiscriminate fusion of the diverse components of G‑d's world, but a regulated integration in which boundaries are respected and the individual qualities of the integrated entities are preserved.

These are two principles to which most everyone will subscribe: the pursuit of unity and the preservation of individuality. The question is always in the particulars—in the who, what, when, where and how of life. Hence the Torah's function as the harbinger of peace in the world. The Torah describes itself as G‑d's "blueprint for creation"--a master plan which details and delineates the manner in which the various components of creation were designed by their Creator to interact and unite. The Torah tells us which entities should be joined together and which should be held apart; it instructs us if, when, and how a given element or force in creation should be integrated into our lives.

Specifically, the Torah's kilayim laws forbid the hybridization of certain species of plants and animals. Three of these laws are enumerated in the 22nd chapter of Deuteronomy:

You shall not sow your vineyard with diverse seeds...

You shall not plow with an ox and a donkey together.

You shall not wear shaatnez, [a garment fashioned of] wool and linen together.

Three Breeds of Hybrid

While the three prohibitions in the above verses all relate to the intermixing of species, each represents a different type of "hybridization."

The first law, which forbids the sowing of grain in a vineyard, is the most extreme form of kilayim among the three. When different plant species are planted in close proximity to each other, their roots intermingle and each derives nourishment from the other. The result is a true hybrid—a plant that has integrated into itself the characteristics of another species. The grape or kernel of grain might not be externally distinguishable from a "normal" grape or kernel, but it has been intrinsically altered, its taste, texture and other qualities affected by the fact that it shared soil and nurture with a different species. This places it in the same class as another form of kilayim (which the Torah forbids in Leviticus 19:19)--the prohibition to breed a hybrid animal by mating two different species to each other.

In contrast, yoking an ox and an donkey to the same plow alters neither the ox nor the donkey. Here, the "hybridization" is not in the species themselves, but in their action. A certain effect has been produced (i.e., a field has been plowed) that is the result of the combined actions of two species.

The third form of kilayim--the prohibition against wearing "shaatnez," a garment made of wool and linen—falls somewhere between the other two types. On the one hand, a tangible entity—the garment—has been created which is itself a combination of two different species. In this sense, the shaatnez garment resembles the hybrid plant produced by mixed sowing. On the other hand, unlike the hybrid plant, whose every fiber and cell has been altered, the wool and linen fibers remain distinct entities within the garment, which can conceivably be disassembled. In this sense, it resembles the second form of kilayim, in which a certain action or effect (in this case, the protection and comfort which the wearer derives from the garment) is jointly produced by two species which themselves remain distinct from each other.

Two Definitions of Shaatnez

Halachic literature records a difference of opinion between two great interpreters of Torah law, Rashi (Rabbi Shlomo Yitzchaki, 1040-1105) and Rabbeinu Tam (Rashi's grandson, Rabbi Yaakov ben Meir, 1100-1171), in regard to the specifics of the shaatnez prohibition. According to Rashi, a garment is shaatnez only if one mixed the raw wool and linen together, combed them together, spun them together, and wove the cloth out of the "hybrid" thread. According to Rabbeinu Tam, a garment is also considered kilayim if each species was combed, spun and woven into cloth individually, and then stitched together as a single garment.1

The Lubavitcher Rebbe explains the reasoning behind these two opinions as deriving from the two vantage points on shaatnez described above. According to Rashi, the prohibition against mixing wool and linen is more closely related to "kilayim of the vineyard." In other words, the garment itself is regarded as the mixed entity, as being neither wool nor linen but a hybrid "species" comprised of two incompatible elements. Since Rashi sees this as the basis of the prohibition, a garment is kilayim only when it most resembles a hybrid species—i.e., when it is thoroughly integrated to the point of indistinguishability. Merely stitching together wool and linen fabrics does not make a "hybrid."

Rabbeinu Tam, on the other hand, sees the law of shaatnez as more closely related to the prohibition to plow with an ox and a donkey together—that is, to benefit from the combined actions of two incompatible species. According to this, the shaatnez garment is no more a "hybrid" than a yoked pair of animals; rather, the essence of the prohibition is that by wearing the garment, the person enjoys the combined effect of two spiritually incompatible materials. So according to Rabbeinu Tam, the degree to which the wool and linen have been blended in the garment-making process is irrelevant, since what makes the garment kilayim is not the intermixing itself, but the fact that wool and linen jointly perform a certain function—specifically, the function of a garment.2

This latter approach (that of Rabbeinu Tam) also explains a certain curiosity in the law of shaatnez: unlike other forms of kilayim, where it is forbidden to create the hybrid entity (as in the prohibition to plant grain and vines together or to mate two species of animals), the laws of shaatnez only forbid the wearing, but not the making, of the mixed garment. In fact, a shaatnez garment can even be used for certain purposes, as long as it does not serve a garment-like function

On the face of it, it would seem that the shaatnez garment is an even more extreme form of hybridization than the other forms of kilayim, and ought to be proscribed by stricter, rather than more lenient, laws. The other forms of kilayim involve the intermixing of different plant species or different animal species; in the case of shaatnez, a plant product (linen) is mixed with an animal product (wool). This seems an even more severe violation of the boundaries of creation. Why, then, is the prohibition against shaatnez limited to the wearing of the mixed garment, while the actual creation of this hybrid entity is permitted?

But the very "severity" of shaatnez is the reason for its seeming leniency. Because wool and linen are so different, they cannot be truly combined, no matter how tightly they are intertwined. Two plants can be grafted to form a third, hybrid species; two animals can be interbred to make a third, mongrel breed. But a plant and an animal cannot be interbred; the only type of kilayim possible in such a combination is the "joint action" type. So until the garment is actually worn, no intermixing has taken place; the two elements are simply coexisting side by side. It is only when the wool and linen fibers act together as a garment that the conflicting forces contained in these two elements clash, disrupting the "peace"--the subtle balance of mutuality and distinctiveness—which Torah endeavors to implement in the world.

The Envelopment of Man

The Kabbalists tell us that the Torah is comprised of a body and a soul. The body of Torah is halachah, the laws and regulations which govern our physical lives; the soul of Torah is its so-called mystical element, which instructs the inner life of the soul. And just as in the human body each organ and cell is vitalized by its corresponding "organ" or "cell" within the soul, so, too, every detail and sub-detail of Torah law has its corresponding "mystical" significance in the soul of Torah.

The same applies to the particulars of the laws of kilayim discussed above: each has its corresponding application in the life of the soul.

The Chassidic masters taught that the "miniature universe" that is man consists, like its macrocosmic counterpart, of four "kingdoms": a mineral or "inanimate" kingdom, a plant kingdom, an animal kingdom and a human kingdom. The "plant kingdom" within the human being are the emotions of the heart, while the "animal kingdom" in man is the intellect. It is in this context that we might understand the spiritual application of the laws of kilayim detailed above.

As a rule, a person should aspire toward an integration and synthesis of the many facets of his emotional and intellectual faculties. But as is the case with the physical universe, there are exceptions to this rule. The various forms of plant kilayim represent those particular traits of the heart whose combination is disruptive, rather than conducive, to emotional harmony. The various forms of animal kilayim represent similar untenable "cross-breeding" in the realm of mind. And the law of shaatnez warns against a certain disruptive union of mind and heart.

But precisely because the mind and heart are so different from each other, the laws warning against their "hybridization" are less constricting. In the case of mixed feelings or cross-wired thought-processes, there is the ever-present danger in the creation of a hybrid—a third "species" which blurs the differences between its progenitors and commingles their qualities in undesirable ways. In the case of the very different realms of mind and heart, however, no such "interbreeding" is possible. So as a rule, the synthesis of mind and heart (no easy task for polarized man) is a positive endeavor.

There is one context, however, in which intellect and feeling must be kept distinct and apart. Kabbalistic teaching distinguishes between two areas of life: "internal" (penimi) and "encompassing" (makkif). Experiences and activities which are absorbed and digested by the person in a controlled manner are regarded as "internal"; experiences and activities which overwhelm the person so that he becomes wholly immersed and absorbed within them are termed "encompassing." In the terminology of Kabbalah, "food" is a metaphor for internalized phenomena, while "garments" is the metaphor for encompassing realities.

An "encompassing" experience can be intellectual or emotional, but it cannot be both. By definition, it is total, all-embracing and one-dimensional. The entire point of such an experience is that the person approaches it without inhibition or equivocation, allowing himself to become totally enveloped within it; that he relates to the truth which it represents in its quintessential simplicity, instead of trying to "capture" it and quantify it with his faculties, as he does in the case of his "internal" endeavors. One cannot relate to an "encompassing" experience in a complex, multi-faceted way; one can only surrender to its pristine simplicity and its singular truth.

Spiritual shaatnez is the attempt to make a "garment" from an admixture of intellect and feeling. There is nothing intrinsically negative in such a composite per se--indeed, the attainment of a synthesis of mind and heart is one of the highest, if most difficult, achievements of man. But such a composite cannot be used as a garment. In all that regards our "encompassing" endeavors, our intellectual and emotional avenues of connection must each be pursued individually, without attempting to combine the "wool" and "linen" of our souls.